Table 2. Photostationary States (Z%) and Determined Half-Lives of the Least Stable Isomer.

entry	compd	Ar	R1	R2	PSS (Z%)	t1/2
1	1a	phenyl	CF3	H	88.6	∼22 days
2	1b	1-naphthyl	CH3	H	-	a
3	1c	2-naphthyl	CH3	H	90.9	1.5 h
4	1d	2-naphthyl	CF3	H	82.0	∼10 days
5	1e	phenyl	CF3	CH3	79.6	∼146 days
6	1f	1-naphthyl	CH3	CH3	89.3	13.1 h
7	1g	2-naphthyl	CH3	CH3	94.3	52.5 h
8	1h	2-naphthyl	CF3	CH3	76.3	∼78 days
9	1i	1-naphthyl	CH3	Ph	84.9	9.5 h
10	1j	1-naphthyl	CH3	2,4-dinitrophenyl	34.2	9.4 h
11	1k	1-naphthyl	CH3	4-tolyl	53.3	9.5 h
12	1l	2-naphthyl	CH3	Ph	92.2	59.8 h
13	1m	2-naphthyl	CH3	2,4-dinitrophenyl	32.9	70.7 h
14	1n	2-naphthyl	CH3	4-tolyl	91.5	44.4 h
15	1o	2-naphthyl	CH3	2-naphthyl	49.0	46.8 h

^aCould not be determined due to very fast thermal back-isomerization.